Advertisements
Advertisements
प्रश्न
Write down the formula for the heat produced when a current I is passed through a resistor R for time t.
Advertisements
उत्तर
H = I2Rt where H is the heat energy produced, I is the current, R is the resistance and t is the time.
APPEARS IN
संबंधित प्रश्न
Why are the conductors of electric heating devices, such as bread-toasters and electric irons, made of an alloy rather than a pure metal?
Give two reasons why nichrome alloy is used for making the heating elements of electrical appliances.
An electric kettle rated at 220 V, 2.2 kW, works for 3 hours. Find the energy consumed and the current drawn.
An electric iron of resistance 20 ohms draws a current of 5 amperes. Calculate the heat produced in 30 seconds.
What is meant by the heating effect of current? Give two applications of the heating effect of current.
The elements of electrical heating devices are usually made of:
(a) tungsten
(b) bronze
(c) nichrome
(d) argon
Which electric heating device in your home do you think have resistors which control the flow of electricity?
In an electric bulb, coil of _______ metal is used.
Write scientific reason.
A coil made up of alloy Nichrome is used in the electric heater cooker as a resistor.
How can overloading be avoided?
Explain the heating effect of electric current.
An electric bulb is connected to a 220 V generator. The current is 0.50 A. What is the power of the bulb?
Your teacher has shown you the following activity.
Activity: Teacher has wound a long insulated piece of wire around an iron nail in the form of a coil. Free ends of the wire are connected to a cell through a switch as shown in the following figure. The current is switched on and some pins are placed near the ends of the nail.
Write down any three questions that come to your mind about this activity.
Fuse is a strip of alloy wire which is made up of lead and tin with a very low ______.
Assertion: A current-carrying wire should be charged.
Reason: The current in a wire is due to the flow of free electrons in a definite direction.
A student boils water in an electric kettle for 20 minutes. Using the same mains supply he wants to reduce the boiling time of water. To do so should he increase or decrease the length of the heating element? Justify your answer.
What is a trip switch?
Tara, after completing her exams, went to her grandmother's house along with her younger brother Rahul. One day, Rahul came home after playing and switched on the fan and air conditioner. At the same time, his grandmother was preparing a milkshake for him using a mixer. Suddenly, they heard a big sound and the electricity of the house got shut down. Tara is called an electrician. He said the main reason for supply to shut down was overloading.
- What is overloading?
- Is overloading and short the same? When does short-circuiting take place?
- How can the effects of overloading be avoided?
An electric kettle consumes 1 kW of electric power when operated at 220 V. A fuse wire of what rating must be used for it?
State the law that explains the heating effect of current with respect to the measurable properties in an electrical circuit.
